The primary objective of this phase IIa, open-label, multi-centre study is to assess the safety, tolerability and immunogenicity of re-dosing at 6 months with an 8 consecutive day series of otelixizumab intravenous (IV) infusions in 8 adult subjects with newly diagnosed type 1 diabetes mellitus (T1DM). Although it is hoped that the β cell preserving effect of otelixizumab will be long-lasting, it is possible that the effect may decline over time and thus T1DM subjects may require re-treatment. Six months is the minimum time expected between treatments.